Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 021915
AFDDTX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
315 PM EDT TUE SEP 2 2014

.SHORT TERM...THROUGH TONIGHT

CURRENT OBSERVATIONS STILL HAVE THE SURFACE COLD FRONT SITUATED
ROUGHLY ALONG A LINE FROM PORT HURON DOWN THROUGH ANN ARBOR.  THIS
HAS BEEN THE FOCUS FOR RAIN AND THUNDERSTORMS TODAY AND WILL
CONTINUE TO BE THE CASE THROUGH THE EARLY EVENING. LATEST
SATELLITE AND RADAR AS OF 3PM SHOW SHOWERS FINALLY DIMINISHING. AREAS
NORTH OF THE BOUNDARY HAVE AND WILL REMAIN DRY THROUGH THE
OVERNIGHT HOURS. ONCE THE FRONT SETTLES OFF TO THE
EAST...RAIN/THUNDERSTORM CHANCES OVER THE SOUTHERN CWA WILL END.
VERY FEW CHANGES WERE MADE TO THE GOING FORECAST WITH THE ONLY
CHANGE BEING TO UP POPS SLIGHTLY ACROSS THE SOUTH THROUGH 21Z.
HIGH PRESSURE WILL SLOWLY TAKE OVER THIS EVENING AND EXTEND
THROUGH THE OVERNIGHT HOURS. DRIER AIR HAS ALREADY BEGUN FILTERING
INTO THE NORTHERN HALF OF THE CWA WHERE DEWPOINTS ARE IN THE
MIDDLE TO UPPER 50S. THIS TREND IS EXPECTED TO CONTINUE WHILE
SLOWLY SCOURING OUT ANY LOW LEVEL LINGERING CLOUDS OVERNIGHT. A
WAS DISCUSSED IN THE PREVIOUS DISCUSSION...A FEW AREAS OF SHALLOW
GROUND FOG MAY BE POSSIBLE ACROSS NORTHERN AREAS EARLY WEDNESDAY
MORNING A LITTLE MOISTURE REMAINS IN THE BOUNDARY LAYER. LOWS
OVERNIGHT WILL BE COOLER THAN THE PREVIOUS NIGHT WITH LOWS RANGING
FROM THE LOWER 60S OVER THE DETROIT METRO AREA TO THE UPPER 50S TO
THE NORTH.

&&

.LONG TERM...

DRY WEATHER AND INCREASING TEMPS ARE ON TAP FOR WEDNESDAY THROUGH
THURSDAY AS HEIGHTS BUILD AND SWLY FLOW INCREASES AHEAD OF THE WAVE
DIGGING INTO THE PACNW THIS AFTERNOON. THIS WAVE WILL SHEAR ACROSS
SOUTHERN CANADA, REACHING JAMES BAY BY FRIDAY. AS IT DOES SO, A
RESPECTABLE LOW-LEVEL JET RESPONSE IS FORECAST TO EMERGE UPSTREAM
SUPPORTING EPISODES OF CONVECTION OVER THE UPPER MS VALLEY. FLOW
WILL ONLY SLOWLY BACK TO SOUTHERLY ON WEDNESDAY WITH LITTLE AIRMASS
CHANGE COMPARED TO TODAY. HOWEVER, WITH GREATER INSOLATION EXPECTED
AS TODAY`S COLD FRONT PROGRESSES EAST, TEMPERATURES SHOULD MODERATE
A FEW DEGREES TO AROUND 80F. WARM ADVECTION THROUGH THE COLUMN WILL
TAKE HOLD ON THURSDAY AS DEEP LAYER SWLY FLOW INCREASES AHEAD OF THE
RAPIDLY APPROACHING PAC NW WAVE. CONVECTION WILL REMAIN TIED TO THE
UPSTREAM THETA-E AXIS/LOW-LEVEL JET. WHILE IT IS NOT OUT OF THE
QUESTION THAT NOCTURNAL REMNANT ACTIVITY APPROACHES THE AREA LATE
WED NIGHT OR THURSDAY MORNING, MUCH PREFER TO LET THE COARSE
RESOLUTION MODELS HANDLE THE SYNOPTIC SCALE AND WILL DEFER TO HIGH
RES ARW/WRF FOR SPECIFICS. AS EXPECTED, THE HIGH RES GUIDANCE DOES
NOT ALLOW ANY SUCH REMNANTS TO REACH THE CWA AND KEEPS CONVECTION
TIED TO UPSTREAM FORECING. AS SUCH, PREFER TO SEE THE WHITE`S OF ITS
EYES SO TO SPEAK BEFORE CLUTTERING THE GRIDS WITH POPS. THE FORECAST
IS THEREFORE DRY THROUGH THURSDAY. INSTEAD, THURSDAY WILL LIKELY BE
CHARACTERIZED BY A FAIR AMOUNT OF CONVECTIVE DEBRIS EARLY,
INCREASING DEWPOINTS, AND H85 TEMPERATURES RISING INTO THE UPPER
TEENS. PER EXPECTATION FOR NO/MINIMAL PRECIP, MAINTAINED FORECAST
HIGHS ON THE WARMER SIDE OF GUIDANCE. TSTORM CHANCES WILL INCREASE
LATE THURSDAY NIGHT AS VEERING LLJ AXIS MIGRATES TOWARD THE AREA.

SHOWERS AND THUNDERSTORMS REMAIN LIKELY FRIDAY AS A COLD FRONT MOVES
THROUGH THE REGION WITH MOIST AND UNSTABLE AIR PRECEDING THE FRONT.
THERE REMAINS A DECENT DENSITY GRADIENT IN PLACE AND ISOLATED SEVERE
WIND GUSTS REMAIN POSSIBLE. COOL HIGH PRESSURE WILL FILL IN BEHIND
THE FRONT FOR SEVERAL DAYS AS TEMPERATURES TREND SEVERAL DEGREES
COOLER THAN NORMAL.

&&

.MARINE...

LIGHT WINDS WILL GIVE WAY TO A MODERATE SOUTHERLY BREEZE THURSDAY
INTO FRIDAY AS A COLD FRONT APPROACHES THE AREA. STABLE WARM
SOUTHERLY FLOW WILL KEEP WIND GUSTS TO A MINIMUM. THERE IS A LOW
CHANCE FOR THUNDERSTORMS ACROSS NORTHERN LAKE HURON ON
THURSDAY...WITH INCREASING CHANCES FOR ALL THE WATERS THURSDAY NIGHT
THROUGH FRIDAY NIGHT.

&&

.AVIATION...ISSUED 118 PM EDT TUE SEP 2 2014

//DISCUSSION...

SURFACE COLD FRONT IS EVER SO SLOWLY SAGGING OFF TO THE
EAST...HOWEVER WITH THE SLOW EXIT RAIN WILL EXIST THROUGH THE
AFTERNOON FOR LOCATIONS SOUTH OF PTK.  ONCE THE FRONT DOES SHIFT OUT
OF THE AREA THIS EVENING...HIGH PRESSURE BUILDS IN OVERNIGHT AND
WILL REMAIN IN PLACE THROUGH THE TAF CYCLE.  WINDS WILL REMAIN LIGHT
AND GENERALLY OUT OF THE WEST/SOUTHWEST.  FOG WAS MENTIONED IN THE
PREVIOUS DISCUSSION AND THE LATEST MODEL SOUNDINGS STILL SHOW LOW
FOG POTENTIAL EARLY WEDNESDAY MORNING WITH SOME GROUND FOG POSSIBLE
ESPECIALLY FOR NORTHERN AREAS.

FOR DTW...CHANCES FOR RAIN WILL CONTINUE THROUGH THE AFTERNOON WITH
A LOW POTENTIAL FOR A THUNDERSTORM.  WINDS WILL GENERALLY REMAIN OUT
OF THE WEST EVEN AS THE FRONTAL BOUNDARY SLIDES EAST THIS AFTERNOON.

//DTW THRESHOLD THREATS...

* LOW CONFIDENCE/POTENTIAL FOR A THUNDERSTORM THROUGH THE AFTERNOON.

* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FEET THROUGH THE EARLY
EVENING.

* MEDIUM CONFIDENCE IN CEILINGS ABOVE 5000 FEET OVERNIGHT.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

$$

SHORT TERM...SS
LONG TERM....JVC/MM
MARINE.......JVC
AVIATION.....SS


YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).





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